Throttle Check Valve Structure for Quiet Priority Flow Control

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Solution Overview

Problem

Priority flow control valves in forklifts experience unwanted vibrations and noise due to spool displacement, leading to unstable hydraulic fluid flow and irritating operational sounds when high pressure hydraulic oil is supplied.

Innovation Solution

Incorporating a throttle check valve with an opening member that separates the poppet valve body from the valve seat when the spool is at the second position, preventing abnormal sounds and maintaining stable operation by ensuring a constant flow path for hydraulic fluid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a throttle check valve is used to stabilize spool operation, then spool stability is improved, but abnormal sounds and vibrations are generated

Engineering Contradiction:
Improvespool stabilityVSAvoidabnormal sounds and vibrations
Core Design Contradiction:
Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

A damping chamber is introduced as an intermediary element between the throttle check valve and the spool. This damping chamber absorbs pressure fluctuations and reduces vibrations, thereby eliminating abnormal sounds while maintaining spool stability provided by the throttle check valve.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the physical parameters of the hydraulic fluid by introducing a damping chamber that modifies pressure wave characteristics. This alters the fluid dynamics to reduce vibration and noise while preserving the stabilizing effect on the spool operation.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the spool position varies to control flowrate, then flow control is achieved, but unwanted speed change and vibration occur

Engineering Contradiction:
Improveflow controlVSAvoidactuator speed stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The damping chamber provides beforehand cushioning by absorbing pressure fluctuations before they can cause unwanted speed changes or vibrations in the actuator. This preemptive damping ensures smooth flow control without destabilizing the actuator operation.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a damping function is provided with a throttle check valve, then spool operation stability is improved, but abnormal sounds are produced

Engineering Contradiction:
Improvespool operation reliabilityVSAvoidabnormal sounds
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The damping chamber serves as an intermediary that decouples the noise-generating throttle check valve from the spool system. It maintains the reliability benefits of the throttle check valve while filtering out abnormal sounds through hydraulic damping.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution suppresses noise production and maintains stable hydraulic fluid flow, preventing unwanted vibrations and ensuring consistent hydraulic fluid supply to steering and loading/unloading ports, enhancing operational stability and reducing operator irritation.

Implementation Method 1

a spring that biases the spool from a first position at which the hydraulic fluid is guided from the high pressure port to the steering port and the loading/unloading port, to a second position at which the hydraulic oil is guided from the high pressure port to the steering port

Methodology Applied
Scientific EffectElastic force: Spring

Implementation Method 2

a throttle check valve with which a flow path for the hydraulic fluid from the steering port to the damper chamber is throttled

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentEP3792503B1Priority flow control valve
Publication Date: 2023.09.06 SHIMADZU CORP
  • EP3792503B1 patent drawingFigure 1
  • EP3792503B1 patent drawingFigure 2
  • EP3792503B1 patent drawingFigure 3

AI summary

A throttle check valve (26) includes: a poppet valve body (31) that has an orifice (32) formed at one end and has a hole portion (35) formed at a side portion; a plug (33) that has a tubular shape to surround the poppet valve body (31), and functions as a valve seat to come into contact with the poppet valve body (31); and a spring (34) that biases the poppet valve body (31) and the plug (33) functioning as the valve seat in directions to come into contact with each other. When the spool (12) is at the second position, the plug (33) forming the distal end portion of the spool (12) and the plug (21) arranged in the housing come into contact with each other. The plug (21) is provided with a protruding portion (27) that comes into contact with the poppet valve body (31).